Are Investors Undervaluing Castle Biosciences, Inc. (NASDAQ:CSTL) By 49%?

Key Insights

• The projected fair value for Castle Biosciences is US$66.66 based on 2 Stage Free Cash Flow to Equity
• Castle Biosciences' US$34.26 share price signals that it might be 49% undervalued
• Analyst price target for CSTL is US$36.11 which is 46% below our fair value estimate

Today we will run through one way of estimating the intrinsic value of Castle Biosciences, Inc. (NASDAQ:CSTL) by projecting its future cash flows and then discounting them to today's value. This will be done using the Discounted Cash Flow (DCF) model. There's really not all that much to it, even though it might appear quite complex.

Companies can be valued in a lot of ways, so we would point out that a DCF is not perfect for every situation. Anyone interested in learning a bit more about intrinsic value should have a read of the Simply Wall St analysis model.

View our latest analysis for Castle Biosciences

The Method

We use what is known as a 2-stage model, which simply means we have two different periods of growth rates for the company's cash flows. Generally the first stage is higher growth, and the second stage is a lower growth phase. In the first stage we need to estimate the cash flows to the business over the next ten years. Where possible we use analyst estimates, but when these aren't available we extrapolate the previous free cash flow (FCF) from the last estimate or reported value. We assume companies with shrinking free cash flow will slow their rate of shrinkage, and that companies with growing free cash flow will see their growth rate slow, over this period. We do this to reflect that growth tends to slow more in the early years than it does in later years.

A DCF is all about the idea that a dollar in the future is less valuable than a dollar today, so we discount the value of these future cash flows to their estimated value in today's dollars:

10-year free cash flow (FCF) forecast

	2025	2026	2027	2028	2029	2030	2031	2032	2033	2034
Levered FCF ($, Millions)	US$14.4m	US$26.7m	US$32.1m	US$43.9m	US$53.0m	US$61.1m	US$68.0m	US$74.0m	US$79.1m	US$83.5m
Growth Rate Estimate Source	Analyst x2	Analyst x2	Analyst x1	Analyst x1	Est @ 20.71%	Est @ 15.24%	Est @ 11.42%	Est @ 8.74%	Est @ 6.87%	Est @ 5.56%
Present Value ($, Millions) Discounted @ 5.8%	US$13.6	US$23.9	US$27.1	US$35.0	US$40.0	US$43.6	US$45.9	US$47.1	US$47.6	US$47.5

("Est" = FCF growth rate estimated by Simply Wall St)
Present Value of 10-year Cash Flow (PVCF) = US$371m

The second stage is also known as Terminal Value, this is the business's cash flow after the first stage. For a number of reasons a very conservative growth rate is used that cannot exceed that of a country's GDP growth. In this case we have used the 5-year average of the 10-year government bond yield (2.5%) to estimate future growth. In the same way as with the 10-year 'growth' period, we discount future cash flows to today's value, using a cost of equity of 5.8%.

Terminal Value (TV)= FCF₂₀₃₄ × (1 + g) ÷ (r – g) = US$83m× (1 + 2.5%) ÷ (5.8%– 2.5%) = US$2.6b

Present Value of Terminal Value (PVTV)= TV / (1 + r)¹⁰= US$2.6b÷ ( 1 + 5.8%)¹⁰= US$1.5b

The total value is the sum of cash flows for the next ten years plus the discounted terminal value, which results in the Total Equity Value, which in this case is US$1.8b. The last step is to then divide the equity value by the number of shares outstanding. Relative to the current share price of US$34.3, the company appears quite good value at a 49% discount to where the stock price trades currently. The assumptions in any calculation have a big impact on the valuation, so it is better to view this as a rough estimate, not precise down to the last cent.

Important Assumptions

Now the most important inputs to a discounted cash flow are the discount rate, and of course, the actual cash flows. If you don't agree with these result, have a go at the calculation yourself and play with the assumptions. The DCF also does not consider the possible cyclicality of an industry, or a company's future capital requirements, so it does not give a full picture of a company's potential performance. Given that we are looking at Castle Biosciences as potential shareholders, the cost of equity is used as the discount rate, rather than the cost of capital (or weighted average cost of capital, WACC) which accounts for debt. In this calculation we've used 5.8%, which is based on a levered beta of 0.800. Beta is a measure of a stock's volatility, compared to the market as a whole. We get our beta from the industry average beta of globally comparable companies, with an imposed limit between 0.8 and 2.0, which is a reasonable range for a stable business.

SWOT Analysis for Castle Biosciences

Looking Ahead:

Although the valuation of a company is important, it is only one of many factors that you need to assess for a company. The DCF model is not a perfect stock valuation tool. Preferably you'd apply different cases and assumptions and see how they would impact the company's valuation. If a company grows at a different rate, or if its cost of equity or risk free rate changes sharply, the output can look very different. What is the reason for the share price sitting below the intrinsic value? For Castle Biosciences, we've put together three additional items you should assess:

1. Risks: Every company has them, and we've spotted 3 warning signs for Castle Biosciences (of which 1 is concerning!) you should know about.
2. Future Earnings: How does CSTL's growth rate compare to its peers and the wider market? Dig deeper into the analyst consensus number for the upcoming years by interacting with our free analyst growth expectation chart.
3. Other High Quality Alternatives: Do you like a good all-rounder? Explore our interactive list of high quality stocks to get an idea of what else is out there you may be missing!

PS. Simply Wall St updates its DCF calculation for every American stock every day, so if you want to find the intrinsic value of any other stock just search here.

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This article by Simply Wall St is general in nature. We provide commentary based on historical data and analyst forecasts only using an unbiased methodology and our articles are not intended to be financial advice. It does not constitute a recommendation to buy or sell any stock, and does not take account of your objectives, or your financial situation. We aim to bring you long-term focused analysis driven by fundamental data. Note that our analysis may not factor in the latest price-sensitive company announcements or qualitative material. Simply Wall St has no position in any stocks mentioned.